“So it serves a very important safety function and they need to test it on a regular basis,” he said. “They did identify a small steam leak involving a governor valve.”

Sheehan said that because the high pressure system is important for reactor safety Yankee has to fix the equipment within 14 days or face a mandatory shutdown.

Vermont Yankee spokesman Rob Williams said the repairs have already been made.

“This was during routine testing (Wednesday) on a pump in the reactor building,” he said. “And technicians noted that there was a small steam leak on a flange associated with that pump. So they took it out of service and reported it to the NRC. It’s since been repaired and retested and it’s back in service.”

Neil Sheehan of the NRC said the leak released a small amount of radioactivity. But he said the leak was contained within the reactor building and was not a threat to public safety.

Entergy, the company that owns Vermont Yankee, announced last month it will close the reactor next year.